How long does a fan run? The short answer: as long as its ball bearing. The service life of the ball bearing is deter­mined by a complex inter­ac­tion of temper­a­ture, speed and lubri­ca­tion. A distinc­tion is made between the mechan­ical service life—often referred to as the L10 service life—and the grease service life, which describes the aging of the lubri­cant. The calcu­la­tion of the mechan­ical service life L10 is described in the DIN ISO 281 stan­dard and spec­i­fies the time until 10 percent of a large number of ball bear­ings fail due to mate­rial fatigue. The mechan­ical service life can be posi­tively influ­enced by the size of the ball bearing and is gener­ally not crit­ical due to the rela­tively low forces in the fan. Instead, the service life of the grease is very often the limiting factor for the service life of the ball bearing and thus also of the fan.

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This grease service life is calcu­lated sepa­rately from the L10 service life and is not stan­dard­ized. The calcu­la­tion is based on ebm-papst’s expe­ri­ence and is calcu­lated from speed-depen­dent recom­men­da­tions for ball bearing relu­bri­ca­tion inter­vals (tf) and temper­a­ture-depen­dent adjust­ment factors (AxT). In the design of the ball bear­ings, both calcu­la­tions (L10 and grease service life) are performed using worst-case data, i.e., oper­a­tion under full load and constantly high temper­a­tures.
As part of its NEXAIRA digital ecosystem, ebm-papst uses real-time fan data for its Fan Health Status service to perform dynamic calcu­la­tions.

Sensors record the speed and temper­a­tures of the envi­ron­ment, the elec­tronics and the motor. An algo­rithm uses this data to calcu­late the bearing temper­a­ture and can deter­mine the remaining service life more accu­rately. The algo­rithm also accesses an internal measure­ment data­base from ebm-papst in order to adapt it indi­vid­u­ally to the respec­tive ball bearing type in the moni­tored fan. If fans run slower than expected—which is often the case in reality—the remaining service life is extended.

In the future, addi­tional sensors will be used to incor­po­rate vibra­tion data into the calcu­la­tion, for example. For customers, this means a real plus in terms of trans­parency and plan­ning reli­a­bility. Knowing how heavily your fans are actu­ally loaded allows you to adjust main­te­nance inter­vals, avoid down­time and plan service calls more effec­tively. Espe­cially in sensi­tive areas such as data centers or clean rooms, where a failure would have serious conse­quences, a simple formula becomes a crucial compo­nent of predic­tive maintenance—and thus of greater effi­ciency and safety during ongoing oper­a­tions.